Oral Presentation 14th Lorne Infection and Immunity 2024

Interferon epsilon as a novel anti-viral agent in the testis (#31)

Rukmali Wijayarathna 1 2 , Eveline de Geus 3 , Rosemary Genovese 1 , Linden J Gearing 2 3 , Michelle Tate 2 3 , Paul J Hertzog 2 3 , Mark P Hedger 1 2
  1. Centre For Reproductive Health, Hudson Institute of Medical Research, Melbourne, Victoria, Australia
  2. Dept. of Molecular and Translational Sciences, School of Clinical Sciences, Monash University, Melbourne, Victoria, Australia
  3. Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Melbourne, Victoria, Australia

Many viruses including Zika, HIV, and SARS viruses can cause persistent infections of the testis. Spermatogenic cells were thought to lack anti-viral protective mechanisms including interferons (IFN) or IFN-stimulated genes (ISGs). Challenging this dogma, we discovered that interferon-epsilon (IFNɛ), a type-I IFN first identified in female reproductive epithelia, is constitutively expressed by spermatogenic cells and macrophages in mouse and human testes. We also discovered that mice lacking IFNɛ are more susceptible to Zika virus induced testicular inflammation. In this study, we examined the mechanisms of IFNɛ-mediated anti-viral defence in the testis.

Sertoli cells constitute the supporting epithelium for spermatogenic cells in the testis. A human Sertoli cell line (HSerc, ScienCell) was infected with Zika virus (MOI 5 or 10). Cultures were treated with 100IU recombinant human IFNɛ 12h before (prophylactic-IFNɛ) or 1h after infection (therapeutic-IFNɛ), or diluent alone (controls). Cells and media were harvested 24h or 48h post-infection for RNAseq, qPCR, and plaque assays.

IFNɛ treatment increased Sertoli cell anti-viral responses and reduced viral infection, with prophylactic-IFNɛ being more effective than therapeutic-IFNɛ treatment. Plaque assays and viral RNA qPCR showed that prophylactic-IFNɛ reduced viral load by approximately 98%. Therapeutic-IFNɛ reduced viral RNA by 70% and infectious virus by 97%. Sertoli cells expressed IFNAR1 and 2 receptors required for IFNɛ signalling. At 24h, both IFNɛ-treatments significantly increased anti-viral effector genes (ISG15, OAS1, IFI35, RSAD2), reduced induction of pro-inflammatory cytokines (CXCL10, CXCL11), and supported expression of Sertoli cell functional genes (INHA). Notably, anti-viral and inflammatory responses were relatively lower at 48h after IFNɛ treatment, compared with 24h, attributable to the reduced viral load. Genes for IFNβ and IFNλ, but not IFNα, were induced by the virus at the time points examined.

These data indicate that IFNɛ induces anti-viral effector responses and reduces inflammatory responses in Sertoli cells, demonstrating the importance of constitutive expression of IFNɛ in the testis to limit viral infection and inflammatory damage.